: Morbidity and Mortality in Marysville, Ohio due to Exposure to Asbestos Contaminated Vermiculite Occupational and environmental exposure to vermiculite mined in Libby, Montana is associated with increased pulmonary morbidity and mortality. This is related to the naturally occurring amphibole fibers that contaminate the vermiculite ore. The ore was mined in Libby for approximately 70 years until 1990 and shipped throughout the U.S. for commercial and residential applications. Significantly elevated rates of pleural and interstitial radiographic changes, decrements in lung function and increases in mortality related to pulmonary disease have been demonstrated in those most heavily exposed occupationally. Adverse health outcomes have also been associated with those with much lower exposures, such as Libby residents and household contacts as well as those exposed occupationally at other U.S. locations. It is unclear, however, what is the lowest level of exposure that can be associated with health effects. In other words, which of the Libby residents, residents near the expander facilities scattered throughout the U.S., or homeowners with Libby vermiculite insulation should be considered at risk for the future development of Libby amphibole associated health effects. The key to answering this question is the ability to generate exposure estimates paired with a well-conducted epidemiological study. The objective of the proposed study is to utilize an existing cohort in Marysville, Ohio (n=513) with over 30 years of latency since initial exposure to relatively low levels of Libby vermiculite for which historical industrial hygiene exposure measurements are available. Previous research with this cohort in 1980 and 2004 has been conducted. However, supplemental exposure data have recently been made available, allowing for the verification and potential refinement of the exposure estimates. Also, previous health endpoints were evaluated with chest X-rays and spirometry. The proposed study will use HRCTs and complete lung function testing to provide more precise and sensitive measurements. With refined exposure estimates, optimum health measurements and six additional years of latency, this study has the potential to clarify the health impact of low level Libby vermiculite exposure, allowing for informed decision making regarding many who have been similarly exposed. Morbidity and Mortality in Marysville, Ohio due to Exposure to Asbestos Contaminated Vermiculite Asbestos contaminated vermiculite mined in Libby, Montana from the 1920's to 1990 has been shown to cause lung cancer and other illnesses. It was shipped to approximately 245 locations throughout the U.S. for industrial use as well as for use in tens of thousands of households for insulation and horticulture activities. A health study of workers who processed Libby vermiculite at a Marysville, Ohio facility will determine the long term health consequences for the thousands of people with relatively low exposures.